Method of making a venetian-blind installation

ABSTRACT

PLANE OF THE LADDER-AND-SLAT ASSEMBLY OF THE BLIND IS INCLINED TO CORRESPOND WITH THE INCLINATION OF THE WINDOW OPENING.   A BUILDING WALL IS INCLINED TO THE VERTICAL AND HAS A WINDOW OPENING THEREIN WHICH IS PROVIDED WITH A VENETIAN BLIND. THE GENERAL PLANE OF THE WINDOW OPENING INCLINES SIMILARLY TO THE INCLINATION OF THE WALL, AND THE

March 20, 1973 DEBS 3,721,285

METHOD OF MAKING A VENETIAN-BLIND INSTALLATION Filed May 29, 1969 2 Sheets-Sheet 1 INVENTOR VICTOR DEBS haw-M ATTO RN EY Marth 20, 1973 v, DEBS 3,721,285

METHOD OF MAKING A VENETIAN-BLIND INSTALLATION Filed May 29, 1989 2 Sheets-Sheet 2 INVENTOR V/c T02 .0533

ATTORN EY United States Patent US. Cl. 160-166 4 Claims ABSTRACT OF THE DISCLOSURE A building wall is inclined to the vertical and has a window opening therein which is provided with a Venetian blind. The general plane of the window opening inclines similarly to the inclination of the wall, and the plane of the ladder-and-slat assembly of the blind is inclined to correspond with the inclination of the window opening.

BACKGROUND OF THE INVENTION Dormer constructions and the like have frequently been used when providing a window opening in an inclined building wall. With these constructions the general plane of the window opening is vertical, despite the inclination of the building wall. The general plane of the window opening being vertical, a Venetian blind can be provided at the window opening in the conventional manner.

A saving in building cost can be effected and other advantages achieved by eliminating dormerlike constructions and allowing the general plane of the window opening to incline similarly to the inclination of the wall. For such an inclined window opening, a conventionallyhung Venetian blind is unsuitable.

SUMMARY OF THE INVENTION The present invention contemplates that tensioned wires will pass through holes in the slats, which may be the lift cord holes; and incline the ladder-and-slat asembly to correspond with the inclination of the general plane of the window opening, the wires being fastened top and bottom.

The present invention provides a method of making the Venetian-blind installation. The method includes the steps of passing the wires through holes in the slats, which may be the lift-cord holes, and fastening the upper ends of the wires to the head of the blind, mounting the head of the blind adjacent the top of the window opening, and then preparing to incline and inclining the plane of the ladder-and-slat assembly by steps which include as to each wire: tensioning the wire, providing an abutment for attachment to the wire and a co-operating fixture for attachment to the building at a predetermined location below the blind, determining the position on the tensioned wire at which the abutment will co-operate in the desired manner with the fixture, attaching the abutment to the wire at such position, and attaching the fixture to the building at the predetermined location.

In accordance with one aspect the method includes the step of attaching the fixtures to the window sill. In accordance with another aspect the fixtures are in co-operating relationship with the wire-attached abutments while the fixtures are being attached to the window sill. In accordance with a further aspect the wires are passed through holes in the fixtures before the co-operating abutments are attached to the wires, holes are provided in the window sill for reception of the wire-attached abutments, and the fixtures are drawn against the window sill by means of screws.

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The presently preferred method of making the installation includes all of the foregoing steps and aspects of the method. The present invention affords additional steps and aspects that will be apparent from the drawing and the description in connection therewith. As regards all of the same, it is left to the user to decide upon the omission of any step or steps, and/or aspect or aspects, which are not needed for this particular purpose.

BRIEF DESORIPTION OF THE DRAWING FIG. 1 is a diagrammatic perspective view showing a Venetian-blind installation in connection with which the method of the present invention may be used.

FIG. 2 is a largely diagrammatic vertical section taken generally on the line 22 of FIG. 1.

FIG. 3 is a fragmentary perspective view showing how the upper end of the wire may be attached to the head of the blind.

FIG. 4 is a fragmentary perspective view showing the attachment of one of the ladders and the associated lift cord to the bottom bar, and showing the associated tensioned wire passing through the bottom bar.

FIG. 5 is a largely diagrammatic vertical section illustrating a step in preparing the lower end of the wire for attachment to the window sill.

FIG. 6 is a detail view illustrating another step in preparing the lower end of the wire for attachment to the Window sill.

FIG. 7 is a detail view similar to FIG. 6 illustrating still another step in preparing the lower end of the wire for attachment to the window sill.

FIG. 8 is a fragmentary perspective view, largely diagrammatic, showing the lower end of the tensioned wire attached to the window sill.

Description of the presently preferred Venetian-blind installation and the presently preferred method of making it The drawings show the presently preferred Venetianblind installation. Except as may be otherwise indicated, the description hereinafter of the Venetian-blind installation (prior to the claims) refers only to the particular form of the installation that is shown in the drawings. As regards the method of making the Venetian-blind installation, the disclosure hereinafter of the method (prior to the claims) is the best mode thus far contemplated of carrying out the method. Nevertheless, the discloure is by way of illustration and example as regards both the Venetian-blind installation and the method of making it; the claims embrace other specific ways in which the method may be carried out.

FIG. 1 shows diagrammatically the corner of a room having a floor 1, a ceiling 2, an outer building wall 3, and a wall 4 which may be either an outer wall of the building or a wall within the building. The floor 1 and the ceiling 2 are horizontal, and the wall 4 is vertical. The wall 3 is inclined to the vertical overlying a portion of the floor that is adjacent to it. The wall 3 is formed with a window opening 5, which has a top face 6 and a bottom face or sill 7. Thelengths of the faces 6 and 7 extend horizontally. However, each of the faces 6 and 7 is an inclined plane that is perpendicular to the face of the wall 3, as is seen in FIGS. 2 and 5. The window opening 5 has jamb faces 8 and 9 which are vertical planes, but the lengths of which incline similarly to the inclination of the wall 3. The general plane of the window opening itself is inclined similarly to the inclination of the wall 3.

The building structure which provides the faces 6, 7, 8 and -9 may be plaster, concrete, brick or the like. In the alternative, some or all of these faces may be on wooden members which are parts of the main building structure, or parts of a window frame that is incorporated in the building structure.

The outside of the window opening is provided with suitable framing and glazing, shown diagrammatically at and 11 in FIGS. 2 and 5. The glazing may be sealed shut or may be arranged for opening and closing, using constructions that are known in the art pertaining to windows.

A Venetian blind is customarily mounted at a window opening in one or the other of two locations with respect to the window opening, viz. nested within the window opening or extending across the window opening without being nested within the window opening. In the drawing hereof the blind is nested Within the window opening. However, the invention may be utilized when the blind extends across the window opening without being nested within the window opening.

The Venetian blind, which is designated as a Whole by B, is mounted at the window opening 5, being nested within it. As will become apparent, many specific forms of Venetian blinds are suitable for the blind B. The particular Venetian blind shown in the drawing hereof has the construction that is disclosed in H. K. Lorentzen et al. U.S. Pat. 3,425,479 issued Feb. 4, 1969, the cradle-andlift-cord organization of the blind being also disclosed in H. K. Lorentzen et al. U.S. application Ser. No. 643,184 filed June 2, 1967, now U.S. Pat. 3,447,585 issued June 3, 1969. The bottom bar and the attachments thereto shown in the drawing hereof, and also the bottom-bar ladder-cap shown in the drawing hereof, are disclosed in H. K. Lorentzen et al. U.S. application Ser. No. 732,144 filed May 27, 1968, now U.S. Pat. 3,485,286 issued Dec. 23, 1969.

The Venetian-blind B includes a ladder-and-slat assembly designated as a whole by 15, this assembly being positioned beneath a head which is designated as a whole by 16. The ladder-and-slat assembly 15 includes a series of slats 17 that are supported and articulated together in known manner by two or more ladders 18, one of which is shown in FIG. 2. The ladder 18 has a front sidepiece 18a and a rear sidepiece 18b, the two sidepieces being interconnected by vertically-spaced crosspieces or rungs 180 on which the slats 17 rest. The ladder shown is of the string type, the sidepieces 18a and 18b being braided cords and each crosspiece 180 being a plurality of filaments which may be braided or twisted into one or more strands. The head 16 consists primarily of a sheet-metal channel 20' and the mechanism that is contained therein, viz.: cradles, a tilt rod, rockers or drums to which the upper ends of the ladder sidepieces 18a and 18b are connected, tilting mechanism to oscillate the tilt rod and rockers, cord guides for the lift cords, and a cord lock to hold the raised or partially raised bottom bar of the blind in adjusted position-all as is well known in the art.

At the bottom of the ladder-and-slat assembly 15 there is a bottom bar, which is the lower edge of the ladder-andslat assembly. The bottom bar, which is designated as a Whole by 40, is a bar such as the bottom bar that is disclosed in application Ser. No. 732,144, now U.S. Pat. 3,481,286; and the lower ends of the ladder sidepieces 18a and 18b are attached to the bottom bar in the manner disclosed in that application and patent. In that application and patent the lower ends of the ladder sidepieces are attached to the bottom bar by means of sheet-metal fittings (sometimes called barbs) which are the same as the fittings or barbs 75, 75 shown in FIG. 4 hereof. In that application and patent the bottom wall 41 of the bottom bar 40* has three holes that are aligned from front to rear, viz. a front hole, a rear hole, and a midpoint hole. The barbs 75, 75 of that application and patent are inserted upwardly through the front and rear holes; the lift cord of that application and patent passes downwardly through the midpoint hole and then is brought back to the interior of the b t om bar th gh a l di y off et o being knotted on the interior of the bottom bar to complete the attachment of the lift cord to the bottom bar. In the Venetian blind B hereof, the ladder sidepieces 18a and 18b and the lift cord 22 are attached to the bottom bar 40 in the same manner as in application U.S. Pat. 3,485,- 286even though in blind B hereof the three aligned holes of the bottom bar of that patent are replaced by the single slot 41a that is shown in FIG. 4 hereof. The front end of slot 41a corresponds with the front hole of U.S. Pat. 3,485,286, the rear end of slot 41a corresponds with the rear hole of -U.S. Pat. 3,485,286, and the middle of slot 41a corresponds with the midpoint hole of U.S. Pat. 3,485,- 286. The barbs 75, 75 are inserted upwardly through the ends of the slot 41a and, once inserted, attach the ladder sidepieces 18a and 13b to the bottom bar in the same manner as in U.S. Pat. 3,485,286. The lift cord 22 passes downwardly at the middle of the slot 41a and is attached to the bottom bar 4-0 in the same manner as in U.S. Pat. 3,485,286.

For each ladder 18 of the Venetian blind B hereof the bottom bar 40 is provided with a plastic ladder-cap, designated as a whole by 20, which is in vertical alignment with the ladder, i.e. the center of the ladder cap is in the plane of the ladder. Except for slotting of the ladder cap, or at least the ladder caps for the end ladders if the blind has more than two ladders, the ladder caps 20 hereof are the same as in U.S. Pat. 3,485,286; and they are attached to the bottom bar in the same manner as in U.S. Pat. 3,485,286.

Each ladder cap 20 for the end ladders 18 of the Venetian blind B hereof is provided with a transverse slot 20:: (FIG. 5) that is midway between the ends of the ladder cap. This slot 20a isnt seen in FIG. 2 because, for clarity of illustration, the ladder cap is shown in end elevation in FIG. 2 even though the general plane of FIG. 2 passes midway between the ends of the ladder cap. The laddercap slot 20a is of the same width and length as the bottombar slot 41a and registers therewith. The slots 20a and 41a are in alignment with the tier of slots 17a which constitute the lift-cord holes in the slats 17. The lift-cord holes 17a have a width which is greater than the thickness of the lift cord 22 and, to afford tilting of the slats, the lift-cord holes 17a have a length which is much greater than the thickness of the lift cord 22. Thus there is ample space for the tensioned wire 50, hereinafter referred to, to pass through the lift-cord holes 17a. The slot 41a in the bottom bar (FIGS. 4 and 5) and the slot 20a in the ladder cap (FIG. 5) afford ample space for the passage of the tensioned wire 58 through the bottom bar and ladder cap for attachment to the building structure beneath the ladderand-slat assembly of the blind (FIGS. 2, 5 and 8).

A tensioned wire 50 is provided in conjunction With the lift cord 22 at each of the so-called end-ladders 18 of the blind B, these ladders being toward the ends of the blind. Additional wires 50 may be provided at intervening ladders and lift cords if there be any. As regards each of the wires 50, the arrangement of the wire and the steps taken in connection with it are the same. Therefore, the description and explanation hereinafter in connection with the wire 50 that is toward one end of the blind will apply to the wire 50 that is toward the other end of the blind, and will apply also to intervening wire or wires 50 if there be any.

As wire for the wire 50 I have used stainless-steel spring-wire having a diameter of approximately .025". For use as wire 50 I cut a piece which is excessively long initially as compared to the extended height of the ladderand-slat assembly 15 of the blind. The upper end of the wire 59 is fastened to the head of the blind, and the lower end of the tensioned wire is fastened to the building structure beneath the ladder-and-slat assembly of the blindthe wire passing through the lift-cord holes in the slats, through the slot 41a in the bottom bar, and through the slot 20a in the ladder cap. The pair of wires 50, one toward each end of the blind comprise means which incline the general plane of the ladder-and-slat assembly to correspond with the general plane of the window opening, as will more fully appear.

Mounted within the head 16 there is a cradle which is designated as a whole by 26. The base 26a of the cradle is against the bottom of the head channel 20 and is provided with a central hole 2611 which registers With a hole (not shown) in the bottom of the head channel to afford vertical passage of the lift cord 22 as shown in FIG. 3. The metal surrounding the hole 26h in the base of the cradle is embossed at 261' in the manner shown in Lorentzen U.S. Pat. 2,872,976; this provides a smooth bearing-surface for the lift cord 22, which comes up through the hole 2611 and then proceeds horizontally to a cord lock at the end of the head. The wire 50 passes upwardly to the interior of the head 16 along with the lift cord 22 and is fastened to the head by being secured to the vertical leg 26b of the cradle 26. The leg 26]) is provided with a small hole 262 through which the wire 50 passes and, beyond the leg, the wire is provided with an enlargement or abutment 50a which engages the leg and prevents withdrawal of the wire 50. The abutment 5611 may be any suitable abutment that can be conveniently attached to the wire 50. A type of abutment that has been used for similar purposes is a metal cylinder that is axially pierced for the passage of the wire and is provided with a radial set-screw to make clamping engagement with the wire. I prefer to use a small-bore seamless copper-sleeve which I telescope onto the wire and then clinch with a plierlike tool of the type used I by electrical workers in crimping small sleeves for making a solderless electrical connection between wires or for attaching a sheet-metal terminal to a wire, the terminal being provided with a sleeve. When crimping the sleeve into holding engagement with the wire 50, I leave a protruding length of wire 50]), which I bend back against the sleeve as is seen in FIG. 3. This provides the wire 50 with a bight which securely holds the sleeve 50a against slipping when the wire is tensioned.

Each of the exceessively long wires 50 can conveniently be placed in the blind and fastened to the head 16 before the blind is mounted, and be left dangling beneath the bottom bar while the blind is being mounted. The order of the steps in placing the Wire in the head may be varied at pleasure. The abutment 50a (FIG. 3) may be attached to the wire 50, after which the wire 50 may be threaded through holes 26t and 26h in the cradle, then through the lift-cord holes 17a in the slats, and thence through the slots 41a and 20a in the bottom bar and ladder cap. Alternatively the wire 50 may be threaded upwardly through the ladder cap and bottom bar, then through the slats, and thence through the holes 26h and 26t in the cradleafter which the abutment 50a is affixed. A second alternative is to begin at the upper slat of the blind, threading the lower end of the wire downwardly through the ladder-and-slat assembly, and threading the upper end of the wire through holes 2611 and 261 in the cradle, and then affixing the abutment 50a to the upper end of the wire.

The blind B is mounted on a pair of suitable installation brackets, various specific forms of suitable brackets being known. For mounting the blind B within the window opening 5, the installation brackets are secured against the jamb faces 8 and 9' adjacent to the tap thereof. Each installation bracket has a fiangelike shelf on which the end of the head channel 20 rests, and each bracket also has a keeper or other suitable means for preventing fortuitous disengaging movement of the end of the head channel. FIGS. 2 and of the drawing show the installation bracket, designated as a whole by 60, which is ecured against the jamb face 9. The installation brackets and their attachment to the building are conventional except that, as shown in FIGS. 2 and 5, the bracket is rotatively displaced so that the flange or shelf 6% on which the end of the head bar rests is inclined by an amount equal to the inclination of the wall 3. However, this gives the installation bracket the same position relative to the wall 3 that it would have if the wall were vertical. The installation bracket which is affixed against the face of jamb 8 for supporting the other end of the head 16 is the same as the bracket 60 but of opposite hand.

With the blind mounted as indicated in FIG. 5, each of the excessively long wires 5t] can reach below the front corner 7a of the bottom face or sill 7 of the window opening. Each wire 50 is to be tensioned and the lower end thereof attached to the window sill at a predetermined location which will place the wires 50, taken together, in a plane that inclines similarly to the inclination of the general plane of the window opening; at the same time each individual wire 50 is to be in a vertical plane which is perpendicular to the general plane of the window opening. Such predetermined location for the wire 56 shown in FIG. 5 is at the center of the bore 7b in the window sill. The attachment of the wire to the building is to be by means of an abutment attached to the wire and a co-operating fixture attached to the building, the fixture being adapted to maintain wire-tensioning pressure on the Wire-attached abutment. In the drawings the fixture for attachment to the building is a flat metal-plate 65 which is provided with a central hole 65a for passage of the wire 5 and provided with countersunk holes 65b, 65b to receive screws 66, 66 (FIG. 8) for securing the plate 65 to the sill 7 and drawing the plate against the sill to maintain the desired tension on the wire. For engagement by the plate 65, the wire 50 is to be provided with a fixed abutment 50d which will be the same as the abutment 56a at the top of the wire.

The blind having been mounted with each wire 50 dangling below the bottom bar 40, I telescope the plate 65 onto the wire and telescope a seamless copper sleeve S onto the wire beneath the plate 65, both as indicated in dotted lines in FIG. 5. Beneath the plate and the sleeve, I telescope onto the wire an axially bored weight W that is provided with a radial thumb-screw Ws for holding the weight in adjusted position on the wire. I fasten the weight W to the wire 50 at a position that will cause the weight to hang substantially below the window sill 7, as is indicated in FIG. 5. The weight W provides the number of pounds tension on the wire 50 that is desired when the wire is attached to the building at the predetermined location. As weight W, I have used a five-pound weight. Under the tension applied by the weight W the wire 50 resiliently elongates to a very slight extent; more important the sheet-steel head-structure, and particularly the sheet-steel channel 21), yield resiliently and allow the depending portion of wire 50 to move downwardly somewhat.

I now locate the sleeve S for forming the wire-attached abutment 50d at the correct position on the wire 50 so that, with the abutment 50d nested in the bore 7b and pulled down by the plate 65 and screws 66, 66, the tension on the wire 56 will be equal to the tension applied by the weight W, e.g. five pounds. Preparatory to determining the position on the wire for the abutment 50d, I crimp the sleeve S into light frictional engagement with the wire 50, thereby holding the sleeve against fortuitous movement on the wire but leaving it adjustable lengthwise of the wire. With a forefinger as indicated at F, I push the wire 50 toward the sill to bring it closely adjacent to the corner 7a of the sill; then I adjust the position of the sleeve S on the wire 50 to bring the upper end of the sleeve to the level of the sill at the top of bore 712. This can be done by eye. In actual practice it can usually be done by merely aligning the top of the sleeve S with the corner 7a, because the height of the window opening is so great as compared to the distance of bore 7b from the sill-corner 7a that the difference in wire-distance to the sill-corner and to the top of bore 7b is the same for practical purposes. The fact that these two distances are the same for practical purposes is lost in the drawing, because in the drawing the proportions are destroyed by the necessity of breaking out the center of the blind and the center of the window opening to fit FIGS. 2 and 5 to the sheet; moreover because of space limitations, FIGS. 2 and 5 show the structure above the break as being in alignment with the structure below the break instead of being displaced to the right.

With the sleeve S correctly positioned along the length of wire 50, the sleeve is fully crimped to form the fixed abutment 50d which is the same as the abutment 50a at the top of the wire. The wire 50 is then cut ofif, leaving a W protruding length of wire 50a (FIG. 6) which is bent back upon the abutment 50d as shown in FIG. 7 to form a b ight which prevents the possibility of the abutment slipping under the tensioning pressure that will be applied by plate 65' The abutment 500' (see FIG. 7) is now swung into alignment with the bore 712 and the screws 66, 66 inserted to attach the lower end of the wire 51) to the window sill as shown in FIG. 8. 1f the sill is of wood, ordinary wood screws may be used. For sills of other material, suitable known fastenings are used to fasten the plate 65. A common arrangement where the sill is of concrete or masonry construction is to use ordinary wood screws but first embed a suitable expansible screw-receiving plug into the building structure of the sill.

In the case of difliculty in locating the abutment 56d at precisely the correct place on wire 59, the abutment may be attached a trifle high on the wire and, if necessary, a shim or shims be used under plate 65 to afford the desired tension on the wire without overtensioning it. One shim 67 is shown in FIG. 2. When the plate 65 is provided with the hole 65a as shown, the plate must be placed on the wire 56) before the abutment 541a is placed on the wire. However, the plate 65 or other fixture use may be provided with a keyhOle slot, or with a slot which extends to the edge, thereby enabling the plate 65 or other fixture to be applied to the wire 51) after the abutment 50!! has been atfixed to the wire.

For the purpose of the present invention the only required modifications of the blind chosen for illustration in the drawings hereof are the provision of means for attaching the wires to the head of the blind and the provision of through openings for the passage of the wires through the bottom bar and ladder cap. Various other specific Venetian blinds may be similarly modified for use in connection with the present invention.

The tensioned wires 50 incline the plane of the ladderand-slat assembly to correspond with the inclination of the general plane of the window opening, as is seen in FIG. 2. The lift cord 22 and lift-cord holes 1712 are in alignment with the ladders as viewed from front to rear of the ladder-and-slat assembly 15; and each wire blends with the lift cord and ladder and is substantially invisible when the blind is fully lowered. The blind can be raised and lowered in normal manner and can be opened and closed in normal manner. When the blind is raised, the wires 50 are exposed below the bottom bar 41!, but they are of such small diameter that they are relatively inconspicuous.

CLAIMS 1. A method of making a Venetian-blind installation in which (1) the blind has a head, has a ladder-and-slat 8 assembly depending from the head, and has wire-receiving holes in the slats, and (2) the blind is at a window opening in a wall that inclines to the vertical, the general plane of the window opening inclining similarly to the inclination of the wall; said method comprising:

providing wires which are excessively long as compared to the extended height of the ladder-and-salt assembly, passing the wires through the wire-receiving holes in the slats and fastening the upper ends of the wires to the head of the blind,

mounting the head of the blind adjacent to the top of the window opening,

and then preparing to incline, and inclining, the plane of the ladder-and-slat assembly to correspond with the inclination of the general plane of the window opening by taking the following steps in respect of each wire:

applying tension to the wire at a level below the bottom of the window opening, providing an abutment for attachment to the wire and providing a co-operating fixture for attachment to the building at a predetermined location below the blind, the fixture when attached to the building being adapted to maintain wire-tensioning pressure on the wire-attached abutment, determining the position on the tensioned wire for the abutment to co-operate with the fixture when the fixture is attached to the building structure at the predetermined location, attaching the abutment to the wire in the position thereon that has been determined and cutting off any portion of the wire beneath the abutment that would be in the way, and attaching the fixture to the building in the predetermined location, the wire-attached abutment being in or being placed in co-operating relation with the fixture.

2. A method of making a Venetian-blind installation as in claim 1 in which the fixtures which maintain the tension on the wires are attached to the window sill.

3. A method of making a Venetian-blind installation as in claim 2 in which the fixtures are in co-operating relation with the wire-attached abutments while being attached to the window sill.

4. A method of making a Venetian-blind installation as in claim 2 in which the wires are passed through holes in the fixtures before the co-operating abutment are attached to the wires, holes are provided in the window sill for the reception of the wire-attached abutments, and the fixtures are drawn against the window sill or shims thereon by means of screws.

References Cited UNITED STATES PATENTS 1,022,415 4/1912 Hannam 172 1,121,022 12/1914 Klassig 160-168 1,752,610 4/193 0 McSpadden 16084 2,328,305 8/1943 Stefano 160172 2,654,425 10/1953 Hayner 160-172 2,860,699 11/1958 Braun 160173 3,425,479 2/1969 Lorentzen et a1 160176 PETER M. CAUN, Primary Examiner UNTTED STATES PATENT oTTTcE QERMMQATE 0F CGRREQTWN Patent No. 9 9 285 Dated March 20, 1973 Inventor (s) VICTOR DEBS It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 8 this should read we his em 3 line 58, after vertical, insert a coma a, Column 3, line 61, "3,481,286" should read w 3,485,286 m Column 4, line 5, "application" should be cancelled, Column 5, line 64, tap should read top em I, Column 7 line 18, "65 should' read 65. Column 8, line 7,

ladderandsalt should read M liadder and sht Signed and sealed this 20th day of November 1973.

(SEAL) Attest:

EDWARD MQFLE'I'CHERPJR. RENE n. TEGTFEYER Attesting Officer Acting Commissioner of Patents FORM F o-10 0 (10-69) USCOMM-DC sows-ps9 9 US. GOVERNMENT PRINTING OFFICE: 1969 O-366-334, i I 

